In electronic circuits, in particular in circuits containing stored information requiring access protection, a problem arises that the circuit must be protected against unauthorized analysis, in particular against covert discovery of the stored data. Such an operation is performed in many cases using an ion beam technique known as the FIB technique (Focused Ion Beam). A measure is described in DE 101 11 027 for protecting electronic circuits from such an analysis or manipulation. In this measure, by way of example, a memory cell to be protected is connected to an antenna by means of which the charge in the memory cell is altered during such an attack. Another disadvantage is that the reprogramming is reversible and can no longer be detected after such a reversal, or memory contents are modified in the interests of the attacker.
Another possibility for carrying out an attack on electronic circuits whose contents are to be protected is to change, for example, the function of the circuit or the contents of memories using radioactive radiation, for example alpha radiation. Such attacks are also effective when the electronic circuit is not operating and could cause deliberate malfunctioning of the electronic circuit.